TRANSFER-FUNCTION ANALYSIS OF CENTRAL ARC OF AORTIC BARORECEPTOR REFLEX IN RABBITS

While electrically stimulating the aortic depressor nerve (ADN) pseudo randomly, we recorded renal sympathetic nerve activity (RSNA) and syst emic arterial pressure (SAP) in 19 alpha-chloralose-anesthetized rabbi ts with sinoaortic denervation. From the recorded signals, we determin ed the transfer functions from ADN stimulation by a pseudorandom binar y sequence to RSNA [H-CMD . RSNA(f)] and to SAP [H-CMD . SAP(f)] The m odulus of H-CMD . RSNA(f) was flat over 0.0122-0.8 Hz, whereas the pha se lag increased linearly with frequency Thus the central transduction appeared not to modify the relative amplitude of the signals from the baroreflex afferents but to provide a fixed time delay (similar to 40 0 ms). In contrast, the modulus of H-CMD . SAP(f) decreased precipitou sly toward high frequencies, and the degree of the phase lag was large r than that of H-CMD . RSNA(f) We conclude that 1) the transfer proper ty of the central are does not significantly modify the relative ampli tude of the frequency components of the baroreflex afferents but provi des a fixed time delay and 2) the frequency independence of the modulu s of the transfer property is not preserved when the analysis is exten ded to SAP.